How do you calculate arcsin(12)?

1 Answer
Jul 20, 2015

Use properties of right angled triangle with sides 12, 12 and 1 to find arcsin(12)=π4

Explanation:

arcsin(12)=α where α[π2,π2] such that sin(α)=12

12 is one side of the right angled triangle with sides:

12, 12 and 1

(Note (12)2+(12)2=12+12=1=12)

This triangle has angles π4, π4 and π2.

So sin(π4)=12

Now sin(θ)=sin(θ)

So sin(π4)=12

So arcsin(12)=π4